1. Field of the Invention
This invention relates to a hydrogenation process comprising the hydrogenation of hydrocarbon materials having olefinic or both olefinic and aromatic unsaturation wherein the olefinic bonds are reduced and when the reaction mixture contains compounds with aromatic unsaturation and/or compounds having both aromatic and olefinic unsaturation, selectively reducing the olefinic unsaturation of such compounds. Thus, this invention relates to the hydrogenation of .alpha. -and internally unsaturated olefins, e.g., such as octadecene-1 and octene-2 and polymeric materials such as copolymers of styrene and butadiene.
Accordingly, this invention more particularly relates to a hydrogenation process wherein such hydrocarbon materials are reacted with hydrogen in the presence of bis(1,5-cyclooctadiene) nickel as catalyst under mild hydrogenation conditions to selectively reduce olefinic bonds without hydrogenating, when present, aromatic unsaturation. In its most particular aspect, this invention is directed to a hydrogenation process wherein polymer materials, e.g., styrene/butadiene copolymers, containing both olefinic and aromatic unsaturation are hydrogenated under mild conditions (from about 400-500 psig and from about 50.degree.-65.degree.C.) in the presence of bis(1,5-cyclooctadiene) nickel as catalyst thereby reducing olefinic bonds of such copolymer without substantial, if any, reduction of their aromatic unsaturation.
2 Description of the Prior Art
The hydrogenation of olefins and olefinic polymers has previously been accomplished. The hydrogenation of olefinic polymers by complex iron, cobalt, nickel salts and alkyl lithium or alkyl aluminum components has been reported in the literature; see for example, J. C. Falk, J. Polymer Science (Part A-1) 9 2617 (1971) and U.S. Pat. No. 3,625,927 (1967).
Polymer hydrogenation has been accomplished, using for example, (1) an organonickel derivative, R Ni (where R= carboxylate or acetyacetone) and (2) an alkyl aluminum or lithium reducing agent. These prior systems, however, have deleterious effects due to extraneous metallic aluminum or lithium residues and possible contamination by carboxylate or acetylacetonatederived moieties in the polymer solution.
Furthermore, polymer hydrogenations in heterogeneous catalyst systems usually require high temperature, high pressure and high catalyst concentration. Under such conditions, the long reaction time may result in saturation of the aromatic rings of a reactant such as polystyrene block. In order to avoid such difficulties, the hereinbelow described catalyst system was developed.